Buffing machine with centerless buffer pad

ABSTRACT

A buffing machine is disclosed for driving a buffer pad constructed with a central cutout portion. A mounting unit for the pad includes a cup shaped member provided with a mouth corresponding in size to the central cutout portion of the buffer pad. The cup shaped member provides for supporting the buffer pad on a backup plate and for connecting the mounting unit to a rotating driving spindle while maintaining a recessed clearance in the central portion of the buffer pad. The structure thus enables the rotating buffer pad to be moved during a buffing operation over a concave contoured surface such that the surface extends into the central cutout portion of the pad without touching the recessed surface of the cup shaped member or the end of the driving spindle connected thereto.

[451 Sept. 11, 1973 1 BUFFING MACHINE WITH CENTERLESS BUFFER PAD [75] Inventor: Orval W. Wakefield, Cypress, Calif.

[73] Assignee: Pit-Bar Manufacturing Company,

Los Angeles, Calif.

22 Filed: June 23,1971

21 Appl.No.: 155,713

[52] US. Cl. l5/230.19, 51/376 [51] Int. Cl B24b 29/00 [58] Field of Search 15/230.l7, 230.19,

[56] References Cited UNITED STATES PATENTS 3,537,832 11/1970 Johnson 51/376 3,100,905 8/1963 Salick 15/235 3,436,876 4/1969 McAvoy et al. 15/246 X 1,779,682 10/1930 Strafford 15/230 UX 1,876,923 9/1932 Hanson 15/230 UX 2,697,840 12/1954 Steele 4/203 "M -A L.

FOREIGN PATENTS OR APPLICATIONS 1,157,718 12/1957 France 51/378 Primary Examiner-Leon G. Machlin Attorney-Beehler, Arant & Jagger [57] ABSTRACT A buffing machine is disclosed for driving a buffer pad constructed with a central cutout portion. A mounting unit for the pad includes a cup shaped member provided with a mouth corresponding in size to the central cutout portion of the buffer pad. The cup shaped member provides for supporting the buffer pad on a backup plate and for connecting the mounting unit to a rotating driving spindle while maintaining a recessed clearance in the central portion of the buffer pad. The structure thus enables the rotating buffer pad to be moved during a buffing operation over a concave contoured surface such that the surface extends into the cen'tral cutout portion of the pad without touching the recessed surface of the cup shaped member or the end of the driving spindle connected thereto.

3 Claims, 4 Drawing Figures BUFFING MACHINE WITH CENTERLESS BUFFER PAD This invention relates to power driven buffing devices and more particularly to a mount for a centerless buffer pad, i.e., a buffer pad constructed with a central cutout portion.

As disclosed and claimed in a co-pending patent ap plication of Orval W. Wakefield, filed on even date herewith, Ser. No. 155,7 1 2 filed June 23, 1971, it is desirable to provide a rotating buffer pad which is constructed such that the central portion of the pad is bare of any working nap inasmuch as this portion of the pad provides very little buffing action and, in fact, is a hindrance to the buffing action, in that it tends to provide a high spot when the buffer pad is held flat against a surface to be buffed, such as to cause the pad to kick to one side when pressure is applied thus making the pad hard to handle. Furthermore, since the central portion of the pad has very little rotating motion and consequently generates an insignificant centrifugal force, any substance such as a cleaner, applied to the buffer pad for use in the buffing action tends to accumulate and wet the dead central portion of the buffer pad such as to render it soggy and ineffective. It is thus seen that it is very desirable to provide a buffer pad with the central portion of the working nap cut out. However, a buffer pad with such a construction cannot be supported by a conventional mount which generally provides for a clamping nut to pass through a small hole in the center of the canvas backing of the buffer pad. Thus in a conventional buffer pad wherein the nap extends to the center of the buffer pad, the nap tends to gather and extend over the clamping nut thus protecting the surface being buffed from having contact therewith. However, when the nap is completely cut away from an enlarged central portion of the pad it leaves the clamping nut exposed which could cause damage to the surface being buffed.

Accordingly the object of the present invention is to provide a novel mounting unit for a centerless buffer pad.

Another object of the present invention is to provide a mounting unit for a centerless buffer pad which enables the pad to be used for polishing surfaces having sharp concave contours without the center of the mounting unit touching and thereby damaging the surface.

Still another object of the invention is to provide a mounting unit for a centerless buffer pad which is fully,

centrally recessed to assurethat the bottom of the mounting unit does not touch the surface being buffed.

These and other objects and advantages-of the present invention will be made apparent from the following description taken in conjunction with the accompanying drawings in which:

FIG. 1 is a perspective view of a buffing device including the buffer pad mounting unit ofv the present invention;

.FIG. 2 is a cross-sectional view of the buffer pad mounting unit as taken along line 2-2 of FIG. 1;

FIG. 3 is a partial plan view, partly sectionalized, of the buffer pad mounting unit in FIG. 2 as taken along line 3-3 thereof; and

FIG. 4 is an exploded view of the component parts comprising the buffing device shown in FIG. 2.

Referring to FlG. 1 of thedrawing, a buffing device 10 is shown which includesthe mounting unit 11 of the present invention. The device 10 comprises a housing 13 which encloses the motor (not shown) used for rotating the driving spindle 14 to which the mounting unit 11 is attached. Housing 13 has a main handle 17 on the back end thereof and a cross rod 18 extending from the side thereof by which the operator handles the buffing device. A cord 19, only a portion of which is illustrated, is connected to an outlet for supplying the power required to drive the motor enclosed within the housing 13.

As shown in FIG. 2, the backing for a buffer pad 15 is formed of a circular sheet of canvas 21 which has its central portion cut away to form an enlarged circular opening 22. The diameter of canvas 21 is typically 8% inches and the diameter of the opening 22 is typically 3 inches. A nap 23 formed of tufts of lambs wool is provided on the front surface of the canvas 21. The tufts of lambs wool, which are approximately 1% inches long, are sewn onto the canvas 21 starting at a point back at the inner edge of its circular opening 22 such as to leave an inner rim 25 of the canvas 21 bare. The central portion of the buffer pad 15 which is not covered with nap comprises acircular area having a diameter which is typically one-third of more of the outer diameter of the canvas 21. The tuft of lambs wool extend generally normal to the canvas backing except near the outer circumferential edge thereof where they tend to lean down intothe plane of the canvas 21. It should be. noted that, for reinforcing purposes, the backing for the buffer pad 15 can be formed of a plurality of sheets of canvas, such as canvas 21, which can be bonded together such as by gluing.

The mounting unit 11 for the buffing device 10 includes a rubber backup plate 27 having an outer diameter smaller than the outer diameter of the canvas 21 and. an enlarged central opening 28 the same size as opening 22 in the canvas 21. The rubber backup plate 27 has a relatively thin outer portion 29 which flares inwardly to form a thicker inner portion 30. A metal cup shaped member 33 is provided with an outer .flange 34 about the mouth thereof whose surface contacts the back of the thicker inner portion 30 of the backup plate 27 and is held in position thereon, such as by the use of a glue. A nut-likemember 37 is located in a central opening on the base of the cup shaped member 33 and welded in position. I

A flat circular reinforcing member 39 fits within the cup shaped member 33 flush with the inner end of the nut-like member 37 and is likewise in position. The circumferential inner surface near the mouth of the cup shaped member 33 is threaded and a cylindrical retaining ring 38 provided with threads on the outer surface thereof threadably engages the threaded cylindrical inner surface of the member 33. The buffer pad 15 is held with its backing of canvas 21 in position against the rubber backup plate 27 by a lip 40 formed on the outerend of the retaining ring 38 which clamps the bare inner rim 25 of the buffer pad 15 and the inner edge of the'backup plate27 against the outer flange 34 of the cup shaped member 33 when the cylindrical portion of the retaining ring 38 is threadably advanced within the cup 33.

In assembling the buffing device 10, the threaded projecting end 31 of the driving spindle 14 threadably engages the nut-like member 37 welded on the base of the cup shaped member. The canvas 21 of the buffer pad 15 is then positioned over the backup plate 27 with its central opening 22 aligned with the central opening 28 of the backup plate 27. The cylindrical retaining ring 38 is then inserted in the mouth of the cup shaped member 33 and threadably engaged therein by the use of a key 41 formed of a flat rectangular piece of metal. The key 41 is inserted within the retaining ring 38 such that the ends of the key 41 engage the lugs 42 provided on the diametrically opposite sides of the inner surface of the retaining ring 38. The key 41 is then manually twisted to advance the retaining ring 38 within the mouth of the cup shaped member 33 until the outer lip 40 of the retaining ring 38 engages the bare inner rim 25 of the central opening 22 of the canvas 21 forming the backing of the buffer pad and thus clamps it against the rubber backup plate 27 which in turn is clamped against the outer flange 34 on the mouth of the cup shaped member 33.

It is thus seen that the mounting unit 11 for the centerless buffer pad 15 is shaped to prevent the recessed inner surface of the cup shaped member 33 from touching a contoured surface being polished by the buffer pad. More particularly, the centerless buffer pad 15 can be held against a surface having a relatively sharp outer contour without making contact with the end 31 of the driving spindle 14 attached to the member 37 on the base of the cup shaped member 33. Furthermore, the use of a mounting unit in the form of a cup shaped member 33 with an open mouth for supporting a buffer pad 15 with the central portion cut out permits all the nap 23 on the working surface of the buffer pad 15 to be placed flat on the surface to be buffed and when pressure is applied the buffer pad runs true with no kicking action.

While the centerless buffer pad mounting unit shown and described herein is admirably adapted to fulfill the features of advantage previously mentioned as-desirable, it is to be understood that the invention is not to be limited to the embodiment shown and described but that the means and construction herein disclosed are susceptible of modification in form, proportion and arrangement of the parts without departing from the principle involved or sacrificing any of its advantages, and the invention is therefore claimed in embodiments of various forms all coming within the scope of the claims which follow.

What is claimed is:

1. A buffing machine with centerless buffer pad, comprising:

a rotatable shaft having power means for driving the same;

a cup shaped member having a bottom wall and a peripheral wall, the end of said shaft being rigidly attached to the center of said bottom wall for rotationally driving said member;

the inner surface of said peripheral wall being threaded, and said cup shaped member also having a circumferential flange projecting outward from the upper edge of said peripheral wall;

a backup plate having a central opening therein whose diameter is as great as the diameter of said inner wall surface, said backup plate having its inner portion supported on said flange but its outer portion extending beyond said flange;

a buffer pad including a canvas backing sheet having a circular central opening therein, and a nap attached to the front surface of said backing sheet; and

a cylindrical retaining ring received within said cup shaped member and having a threaded external surface which engages said threaded peripheral wall, said retaining ring on its outer end having a circumferential flange which grasps the inner portion of said buffer pad and holds the same tightly against said backup plate and said flange of said cup-shaped member;

wherein a portion of the inner rim of said canvas backing sheet is bare of any nap, and said retaining ring flange grasps only said bare backing sheet portion of said buffer pad.

2. A buffing machine with centerless buffer pad,

comprising:

a rotatable shaft having power means for driving the same;

a cup shaped member having a bottom wall and a peripheral wall, the end of said shaft being rigidly attached to the center of said bottom wall for rotationally driving said member;

the inner surface of said peripheral wall being threaded, and said cup shaped member also having a circumferential flange projecting outward from the upper edge of said peripheral wall;

a backup plate having a central opening therein whose diameter is as great as the diameter of said inner wall surface, said backup plate having its inner portion supported on the lower side of said flange and its outer portion extending beyond said flange;

a buffer pad including a canvas backing sheet having a circular central opening therein, and a nap at-' tached to the front surface of said backing sheet; and

a cylindrical retaining ring received within said cup shaped member and having a threaded external surface which engages said threaded peripheral wall, said retaining ring on its outer end having a circumferential flange which grasps the inner portion of said buffer pad and holds the same tightly against said backup plate and said flange of said cup-shaped member;

wherein a pair of lugs are provided on the interior wall of said retaining ring whereby a tool may be inserted therein for screwing said retaining ring into said cup shaped member;

the interior of said retaining ring providing free access' for insertion of the tool.

3. A mounting unit for a buffer pad having a central portion thereof cut out, comprising:

a cup shaped member having a bottom wall, means for attaching a drive shaft to the center of said bottom wall, a peripheral wall surrounding said bottom wall, said peripheral wall having an opening on the mouth of said cup shaped member corresponding to the central cut out portion of said buffer pad, the inner surface of said peripheral wall being threaded near said mouth, and a circumferential flange projecting outward from the mouth of said peripheral wall;

a backup plate having a central opening therein which corresponds to said mouth, said backup plate having its inner portion supported on said flange of said cup shaped member on the side thereof which faces towards said bottom wall, with the outer portion of said backup plate extending beyond said flange; and

wherein a pair of lugs are provided on the inner wall of said retaining ring, whereby a tool may be inserted into said ring for screwing said ring securely into said cup shaped member;

the interior of said retaining ring providing free access for insertion of the tool. 

1. A buffing machine with centerless buffer pad, comprising: a rotatable shaft having power means for driving the same; a cup shaped member having a bottom wall and a peripheral wall, the end of said shaft being rigidly attached to the center of said bottom wall for rotationally driving said member; the inner surface of said peripheral wall being threaded, and said cup shaped member also having a circumferential flange projecting outward from the upper edge of said peripheral wall; a backup plate having a central opening therein whose diameter is as great as the diameter of said inner wall surface, said backup plate having its inner portion supported on said flange but its outer portion extending beyond said flange; a buffer pad including a canvas backing sheet having a circular central opening therein, and a nap attached to the front surface of said backing sheet; and a cylindrical retaining ring received within said cup shaped member and having a threaded external surface which engages said threaded peripheral wall, said retaining ring on its outer end having a circumferential flange which grasps the inner portion of said buffer pad and holds the same tightly against said backup plate and said flange of said cup-shaped member; wherein a portion of the inner rim of said canvas backing sheet is bare of any nap, and said retaining ring flange gRasps only said bare backing sheet portion of said buffer pad.
 2. A buffing machine with centerless buffer pad, comprising: a rotatable shaft having power means for driving the same; a cup shaped member having a bottom wall and a peripheral wall, the end of said shaft being rigidly attached to the center of said bottom wall for rotationally driving said member; the inner surface of said peripheral wall being threaded, and said cup shaped member also having a circumferential flange projecting outward from the upper edge of said peripheral wall; a backup plate having a central opening therein whose diameter is as great as the diameter of said inner wall surface, said backup plate having its inner portion supported on the lower side of said flange and its outer portion extending beyond said flange; a buffer pad including a canvas backing sheet having a circular central opening therein, and a nap attached to the front surface of said backing sheet; and a cylindrical retaining ring received within said cup shaped member and having a threaded external surface which engages said threaded peripheral wall, said retaining ring on its outer end having a circumferential flange which grasps the inner portion of said buffer pad and holds the same tightly against said backup plate and said flange of said cup-shaped member; wherein a pair of lugs are provided on the interior wall of said retaining ring whereby a tool may be inserted therein for screwing said retaining ring into said cup shaped member; the interior of said retaining ring providing free access for insertion of the tool.
 3. A mounting unit for a buffer pad having a central portion thereof cut out, comprising: a cup shaped member having a bottom wall, means for attaching a drive shaft to the center of said bottom wall, a peripheral wall surrounding said bottom wall, said peripheral wall having an opening on the mouth of said cup shaped member corresponding to the central cut out portion of said buffer pad, the inner surface of said peripheral wall being threaded near said mouth, and a circumferential flange projecting outward from the mouth of said peripheral wall; a backup plate having a central opening therein which corresponds to said mouth, said backup plate having its inner portion supported on said flange of said cup shaped member on the side thereof which faces towards said bottom wall, with the outer portion of said backup plate extending beyond said flange; and a cylindrical retaining ring having its external surface threaded, and adapted to be received within said cup shaped member in engagement with said threaded wall thereof, said retaining ring on its outer end having a circumferential flange adapted to securely grasp the inner portion of the buffer pad and hold the same tightly against said backup plate and said flange of said cup-shaped member; wherein a pair of lugs are provided on the inner wall of said retaining ring, whereby a tool may be inserted into said ring for screwing said ring securely into said cup shaped member; the interior of said retaining ring providing free access for insertion of the tool. 